Resonant magnetic perturbations (RMPs) used to control type-I edge-localized modes produce a splitting of the peaks of heat flux profile on the divertor. The additional peaks can appear outside the areas connected to the plasma core by the perturbed field lines due to perpendicular transport. This effect has been studied so far using demanding three-dimensional transport simulations. We present a simple method to quantitatively estimate the heat flux profile that the RMP will produce on the divertor. The method needs only field line tracing to determine the so-called tangle distance function, and knowledge of the heat flux profile on the unperturbed heat flux profile. We find good agreement between this method and a transport simulation.